Aspinall Unit Spring Peak Operations Update

From email from Reclamation (Erik Knight):

The spring peak operation is nearing completion. The peak release period of the spring peak operation has concluded. Flows at the Whitewater gage were over 14,350 cfs for six days and a peak daily flow of 16,500 cfs occurred on June 9th.

The ramp down period has begun and releases will continue to be decreased through Thursday, June 20th. The ramp down schedule is shown below. Daily flows for the Gunnison River below the Gunnison Tunnel should be considered as approximations. Actual flows may vary from the numbers below if side inflows to Crystal Reservoir increase or decrease the spill rate beyond what is currently forecast.

#Runoff/#Snowpack news: It looks like Blue Mesa Reservoir will fill this year

From The Grand Junction Daily Sentinel (Dennis Webb):

Aldis Strautins, hydrologist for the National Weather Service in Grand Junction, said so far snow has been melting off in a manageable fashion, with some minor flooding in lowland locations but nothing serious so far.

“We’re not totally out of the woods yet. It bears monitoring and keeping aware of the situation,” he said.

He said the Colorado River is coming up and may peak locally around Sunday. Andy Martsolf, emergency services director for the Mesa County Sheriff’s Office, said flows on the Colorado River at the state line are expected to peak at about 36,000 cubic feet per second this weekend. That’s up considerably from the 24,900 cfs being reported there by the U.S. Geological Survey Wednesday.

Officials expect a possible second peak later this month.

The Gunnison River already is cranking, but that’s by design, under the operational protocol for the Aspinall Unit dams on the river. Erik Knight, a hydrologist with the Bureau of Reclamation, said releases began on Saturday in an attempt to hit a target goal of flows of 14,350 cfs for 10 days on the lower Gunnison at Whitewater, to help critical habitat for endangered fish in that stretch.

He said it appears flows will fall 1,000 cfs short of that goal.

The National Weather Service has issued a flood advisory in the lower Gunnison River due to the extra water releases affecting river levels there. Strautins said it wasn’t a flood warning, but an effort to make people aware of dangers such as banks giving way due to the high water.

Knight said it doesn’t appear that flows through Delta will exceed 13,000 cfs during the 10-day release. That’s below the level at which the Bureau of Reclamation would cut back releases during the 10-day period to protect the community from flooding.

Wilma Erven, Delta’s parks, recreation and golf director, said some water is showing up in a park at the confluence of the Gunnison and Uncompahgre rivers, something that can occur in years like this one…

Strautins pointed to a mix of warmer and cooler weather in the forecast in coming days as opposed to a prolonged hot stretch that could drive water levels particularly high, with cloud cover also expected to moderate melting of snow.

Knight, who several months ago could hardly have imagined Blue Mesa Reservoir filling this year after last year’s low snowpack and drought, said it now appears almost certain to fill…

…the snowpack levels remaining in areas such as southwest Colorado are impressive, as evidenced by the mere fact that many sites that normally are dry by now still have snow.

According to one of the data sets [Brian] Domonkos uses, current snowpack levels in those combined basins and in the Gunnison basin are the second-highest on record, he said. But peak levels this year in basins in western Colorado don’t compare nearly as well to other high snowpack years, with the southwest Colorado basins ranking perhaps fourth or fifth, and other basins not coming in that high, Domonkos said.

He said one of his statistical tools indicates there are about 12.3 inches of snow water equivalent left in the Gunnison basin, which peaked at 24 inches.

“So we’re halfway through the melt of that peak snowpack,” he said.

The Colorado basin has about 11 inches of snow water equivalent left, after peaking at about 20 inches, Domonkos said.

He said snowpack normally melts at a rate of an inch a day or a little less of snow water equivalent.

“So snowpack on average probably won’t be hanging around too much longer,” he said.

While more than half of the Colorado basin’s snowpack already is melted, that snowpack was above-average, and Martsolf said the remaining snowpack is still about 71 percent of an average peak snowpack for the basin.

“We’re definitely melted off from where we would be for a seasonal peak but we still have a ways to go,” he said…

Nowhere in western Colorado is the combined threat of rising rivers and avalanche debris causing more concern than in Hinsdale County. Federal, state and county funding is paying the nearly $1 million cost for the ongoing, emergency removal of the historic, defunct Hidden Treasure Dam. While it no longer holds water, there’s concern that avalanche debris washing down Henson Creek combined with high water flows could destroy it, releasing water and debris and causing downstream flooding…

Both Henson and the Lake Fork of the Gunnison creeks pose threats to Lake City. Lyon said there’s currently no flooding occurring, but creek levels have come up considerably in recent days. Warming temperatures and possible rainstorms both could influence what ultimately occurs in coming days and weeks.

#Runoff news: Inflows to Blue Mesa Reservoir = ~200,000 acre-feet as of May 20, 2019

From The Vail Daily (Scott N. Miller) via The Aspen Times:

At the Eagle River Water & Sanitation District’s May 20 State of the River gathering, participants heard a presentation from Karl Wetlaufer, a hydrologist and assistant supervisor with the U.S. Department of Agriculture’s Natural Resources Conservation Service.

Wetlaufer talked about state and regional snowpack and provided some streamflow forecasts. The news was good on both topics.

It isn’t just the Eagle River drainage that’s had a good snow year. Across Colorado, the average “snow water equivalent” in the snowpack stands at 186 percent of the 30-year median. After the drought of 2018, that’s fantastic news.

According to Wetlaufer, Southern Colorado — the part of the state that most needed a big snow year — was the area where the snowpack is greatest. The snowpack in the San Juan, Dolores, Animas and San Juan River basins — closest to the Four Corners area — stood at 294 percent of the median on May 20.

Wetlaufer said that runoff so far has added about 200,000 acre feet of water to one of the state’s biggest reservoirs, Blue Mesa, near Gunnison. At the end of 2018, that reservoir was at its lowest level since 1984.

All the good news across the state is good news to local fishing guides and raft companies.

Sage Outdoor Adventures has a permit to raft Gore Creek through Vail. That didn’t happen last year. Cole Bangert of Sage said in an average year, the company can run raft trips through Vail for three or four weeks per season, mostly in June.

Bangert said he expects a longer season this year, due both to abundant snow and a slow melt so far.

Clear Creek Canyon via Bob Berwyn

From CBS 4 Denver (Michael Abeyta):

[Bruce Becker] says with all the snow we’ve been getting, water flow in the state’s rivers could be the highest we’ve seen since 2011 or 2013…

Add to that the cool start we’ve gotten to the season and conditions are almost perfect for a long and fun season…

Whitewater rafting and kayaking outfitters across the state hope Becker is right because last year’s hot dry summer and winter really hurt business.

“Our other outfitters in southwest Colorado practically had no season. My season on Clear Creek which is my main run was cut a month short and when you only have three months, losing one month hurts.”

On Sunday, a man was in Becker’s office booking a trip for late July. With folks already booking their trips months in advance, he is optimistic this summer on the river will be a good one for everyone.

Aspinall Unit operations update: Crystal Reservoir spill forecasted for May 27, 2019

Aspinall Unit

From email from Reclamation (Erik Knight):

The May 15th forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 990,000 acre-feet. This is 147% of the 30 year average. Snowpack in the Upper Gunnison Basin peaked at 143% of average. Blue Mesa Reservoir current content is 457,000 acre-feet which is 55% of full. Current elevation is 7473.2 ft. Maximum content at Blue Mesa Reservoir is 829,500 acre-feet at an elevation of 7519.4 ft.

Based on the May forecasts, the Black Canyon Water Right and Aspinall Unit ROD peak flow targets are listed below:

Black Canyon Water Right
The peak flow target is equal to 7,158 cfs for a duration of 24 hours.
The shoulder flow target is 966 cfs, for the period between May 1 and July 25.

Aspinall Unit Operations ROD
The year type is currently classified as Moderately Wet.
The peak flow target will be 14,350 cfs and the duration target at this flow will be 10 days.
The half bankfull target will be 8,070 cfs and the duration target at this flow will be 20 days.
(The criteria have been met for the drought rule that allows half-bankfull flows to be reduced from 40 days to 20 days.)

Pursuant to the Aspinall Unit Operations ROD, releases from the Aspinall Unit will be made in an attempt to match the peak flow of the North Fork of the Gunnison River to maximize the potential of meeting the desired peak at the Whitewater gage, while simultaneously meeting the Black Canyon Water Right peak flow amount. The latest forecast for flows on the North Fork of the Gunnison River keeps river flows below their projected peak flow level for most of the 10 day forecast period. Warmer weather and higher flows are forecast to return by the first days of June.

Therefore ramp up for the spring peak operation will begin on Wednesday, May 22nd, with the intent of timing releases with this potential higher flow period on the North Fork of the Gunnison River. Releases from Crystal Dam will be ramped up according to the guidelines specified in the EIS, with 2 release changes per day, until Crystal begins to spill. The release schedule for Crystal Dam is:

Crystal Dam will be at full powerplant and bypass release on May 26th. Crystal Reservoir will begin spilling by May 27th and the peak release from Crystal Dam should be reached on May 30th or 31st. The flows in the Gunnison River after that date will be dependent on the timing of the spill and the level of tributary flow contribution. Estimates of those numbers will be determined in the upcoming days.

The current projection for spring peak operations shows flows in the Gunnison River through the Black Canyon between 7,000 cfs and 8,000 cfs for 10 days in order to achieve the desired peak flow and duration at Whitewater. Actual flows will be dependent on the downstream contribution of the North Fork of the Gunnison River and other tributaries. Higher tributary flows will lead to lower releases from the Aspinall Unit and vice versa.

Crystal dam spilling May 2009

Aspinall unit operations update: Blue Mesa Reservoir is currently projected to fill to an approximate peak content of 795,000 acre-feet

Blue Mesa Reservoir

From email from Reclamation (Erik Knight):

The May 1st forecast for the April – July unregulated inflow volume to Blue Mesa Reservoir is 970,000 acre-feet. This is 144% of the 30 year average. Snowpack in the Upper Gunnison Basin peaked at 143% of average. Blue Mesa Reservoir current content is 384,000 acre-feet which is 46% of full. Current elevation is 7462 ft. Maximum content at Blue Mesa Reservoir is 829,500 acre-feet at an elevation of 7519.4 ft.

Based on the May 1st forecast, the Black Canyon Water Right and Aspinall Unit ROD peak flow targets are listed below:

Black Canyon Water Right
The peak flow target is equal to 7,158 cfs for a duration of 24 hours.
The shoulder flow target is 966 cfs, for the period between May 1 and July 25.

Aspinall Unit Operations ROD
The year type is currently classified as Moderately Wet.
The peak flow target will be 14,350 cfs and the duration target at this flow will be 10 days.
The half bankfull target will be 8,070 cfs and the duration target at this flow will be 20 days.
(The criteria have been met for the drought rule that allows half-bankfull flows to be reduced from 40 days to 20 days.)

Projected Spring Operations
During spring operations, releases from the Aspinall Unit will be made in an attempt to match the peak flow of the North Fork of the Gunnison River to maximize the potential of meeting the desired peak at the Whitewater gage, while simultaneously meeting the Black Canyon Water Right peak flow amount. The magnitude of release necessary to meet the desired peak at the Whitewater gage will be dependent on the flow contribution from the North Fork of the Gunnison River and other tributaries downstream from the Aspinall Unit. Current projections for spring peak operations show that flows in the Gunnison River through the Black Canyon could be over 8,000 cfs for 10 days in order to achieve the desired peak flow and duration at Whitewater. With this runoff forecast and corresponding downstream targets, Blue Mesa Reservoir is currently projected to fill to an elevation of around 7515.5 feet with an approximate peak content of 795,000 acre-feet.

Aspinall Unit operations update: 960 CFS in Black Canyon

Sunrise Black Canyon via Bob Berwyn

From email from Reclamation (Erik Knight):

Releases from the Aspinall Unit will be increased by 130 cfs on Friday, May 3rd. This will bring flows in the Gunnison River through the Black Canyon up to shoulder flow levels, as described in the decree for the Black Canyon water right. The current forecast for the April-July runoff volume for Blue Mesa Reservoir is 970,000 AF of inflow, which is 144% of average. Flows in the lower Gunnison River are currently above the baseflow target of 1050 cfs. River flows are expected to stay above the baseflow target for the foreseeable future.

Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 1050 cfs for May.

Currently, diversions into the Gunnison Tunnel are 680 cfs and flows in the Gunnison River through the Black Canyon are around 830 cfs. After this release change Gunnison Tunnel diversions will still be 680 cfs and flows in the Gunnison River through the Black Canyon will be around 960 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

Aspinall Unit operations update: 825 cfs through Black Canyon

Looking downstream from Chasm View, Painted Wall on right. Photo credit: NPS\Lisa Lynch

From email from Reclamation (Erik Knight):

Releases from the Aspinall Unit will be increased by 250 cfs on Wednesday, May 1st. This will bring flows in the Gunnison River through the Black Canyon up to shoulder flow levels, as described in the decree for the Black Canyon water right. The current forecast for the April-July runoff volume for Blue Mesa Reservoir is 860,000 AF of inflow, which is 127% of average. Flows in the lower Gunnison River are currently above the baseflow target of 1050 cfs. River flows are expected to stay above the baseflow target for the foreseeable future.

Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 1050 cfs for April and May.

Currently, diversions into the Gunnison Tunnel are 675 cfs and flows in the Gunnison River through the Black Canyon are around 575 cfs. After this release change Gunnison Tunnel diversions will still be 675 cfs and flows in the Gunnison River through the Black Canyon will be around 825 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.